w1: ds1wm: fix register offset (bus shift) calculation

Replace incorrect register offsett calculation by
direct configuration of bus_shift in mfd-cell.

Indirect definition of address-shift by resource size
was unobvious and was wrong (should have used a binary log).

Signed-off-by: Johannes Poehlmann <johannes.poehlmann@izt-labs.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/w1/masters/ds1wm.c b/drivers/w1/masters/ds1wm.c
index fd2e9da..401e53e 100644 (file)
--- a/drivers/w1/masters/ds1wm.c
+++ b/drivers/w1/masters/ds1wm.c
@@ -95,7 +95,7 @@ static struct {
 
 struct ds1wm_data {
        void     __iomem *map;
-       int      bus_shift; /* # of shifts to calc register offsets */
+       unsigned int      bus_shift; /* # of shifts to calc register offsets */
        struct platform_device *pdev;
        const struct mfd_cell   *cell;
        int      irq;
@@ -473,9 +473,6 @@ static int ds1wm_probe(struct platform_device *pdev)
        if (!ds1wm_data->map)
                return -ENOMEM;
 
-       /* calculate bus shift from mem resource */
-       ds1wm_data->bus_shift = resource_size(res) >> 3;
-
        ds1wm_data->pdev = pdev;
        ds1wm_data->cell = mfd_get_cell(pdev);
        if (!ds1wm_data->cell)
@@ -484,6 +481,24 @@ static int ds1wm_probe(struct platform_device *pdev)
        if (!plat)
                return -ENODEV;
 
+       /* how many bits to shift register number to get register offset */
+       if (plat->bus_shift > 2) {
+               dev_err(&ds1wm_data->pdev->dev,
+                       "illegal bus shift %d, not written",
+                       ds1wm_data->bus_shift);
+               return -EINVAL;
+       }
+
+       ds1wm_data->bus_shift = plat->bus_shift;
+       /* make sure resource has space for 8 registers */
+       if ((8 << ds1wm_data->bus_shift) > resource_size(res)) {
+               dev_err(&ds1wm_data->pdev->dev,
+                       "memory resource size %d to small, should be %d\n",
+                       (int)resource_size(res),
+                       8 << ds1wm_data->bus_shift);
+               return -EINVAL;
+       }
+
        res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
        if (!res)
                return -ENXIO;

diff --git a/include/linux/mfd/ds1wm.h b/include/linux/mfd/ds1wm.h
index 38a372a..79a01e8 100644 (file)
--- a/include/linux/mfd/ds1wm.h
+++ b/include/linux/mfd/ds1wm.h
@@ -1,13 +1,23 @@
-/* MFD cell driver data for the DS1WM driver */
+/* MFD cell driver data for the DS1WM driver
+ *
+ * to be defined in the MFD device that is
+ * using this driver for one of his sub devices
+ */
 
 struct ds1wm_driver_data {
        int active_high;
        int clock_rate;
-       /* in milliseconds, the amount of time to */
-       /* sleep following a reset pulse. Zero    */
-       /* should work if your bus devices recover*/
-       /* time respects the 1-wire spec since the*/
-       /* ds1wm implements the precise timings of*/
-       /* a reset pulse/presence detect sequence.*/
+       /* in milliseconds, the amount of time to
+        * sleep following a reset pulse. Zero
+        * should work if your bus devices recover
+        * time respects the 1-wire spec since the
+        * ds1wm implements the precise timings of
+        * a reset pulse/presence detect sequence.
+        */
        unsigned int reset_recover_delay;
+
+       /* left shift of register number to get register address offsett.
+        * Only 0,1,2 allowed for 8,16 or 32 bit bus width respectively
+        */
+       unsigned int bus_shift;
 };